1. Field of the Invention
The present invention relates to a developing apparatus and a cleaning apparatus suitable for use in an image forming apparatus such as a printer, a copying machine, a facsimile or the like.
2. Description of the Related Art
One example of a conventional process cartridge detachable from an image forming apparatus will hereinafter be described with reference to FIGS. 13 to 16. In FIG. 13 and FIG. 14, numeral 101 refers to a developing roller as a developing agent carrier, and a developing blade 102 as a developing agent layer thickness regulating member, disposed in parallel with a longitudinal direction of the developing roller 101, is disposed in direct contact with a surface of the developing roller 101. Both ends of the developing blade 102 are secured by screws to seat surfaces 104a of a developing container 104.
As shown in FIG. 14, a pressingly contacting force between the developing blade 102 and the developing roller 101 is controlled by a flexure angle xcex81 of an elastic portion 102a. 
In FIG. 16, numeral 105 is a photosensitive drum, and a cleaning blade 106 as a cleaning member, disposed in parallel with a longitudinal direction of the photosensitive drum 105, is disposed in direct contact with a surface of the photosensitive drum 105. Similarly, the cleaning blade 106 is secured by screws 103 to seat surfaces 107a of a cleaning frame 107.
As shown in FIG. 16, a pressingly contacting force between the cleaning blade 106 and the photosensitive drum 105 is controlled by a spacing distance (intrusion amount) Q between a virtual position of a tip of an elastic portion 106a of the cleaning blade 106 without the photosensitive drum 105 and a directly contacting point Y of the elastic portion 106a with the photosensitive drum 105, and also by a flexure angle xcex82 of the elastic portion 106a. 
In the aforementioned conventional example, however, internal temperature of the image forming apparatus changes due to influences such as installation environment or fixing device temperature, and accompanied by this change, temperatures of respective parts inside the process cartridge change, too. When the temperature inside the apparatus rises, the developing container 104 and the developing blade 102 are elongated in right and left directions in FIG. 15 (in an arrow a direction) according to respective coefficients of thermal expansion.
At this time, as for the developing container 104 made of resin and a sheet metal portion 102b, made of metal, of the developing blade 102, the developing container 104 made of resin has a larger coefficient of liner thermal expansion (a typical resin has a coefficient of liner thermal expansion of 7xc3x9710xe2x88x925; iron has a coefficient of liner thermal expansion 1.12xc3x9710xe2x88x925) and a larger elongation than those of the sheet metal portion 102b, thereby deforming the sheet metal portion in a downward direction in FIG. 15 (in an arrow b direction) based on screws 103 as base points provided in two spots, and therefore, the flexure angle xcex81 at a center portion in a longitudinal direction of the developing blade 102 shown in FIG. 14 becomes smaller, with the result that a pressingly contacting force of the developing blade 102 with respect to the developing roller 101 becomes lower at the center portion in the longitudinal direction.
When a pressingly contacting force of the developing blade 102 becomes lower at the center portion of the longitudinal direction, a thickness of a toner coat and a frictionally sliding charging amount on the developing roller 101 become reduced, and therefore an image density at the center portion in the longitudinal direction becomes lowered, which might cause image unevenness.
For example, it has experimentally proved that, provided that a length of the securing portions (a spacing distance between holes for the screws 103 of the end portions) of the sheet metal portion 102b of the developing blade 102 is 211 mm and the temperature is changed to 30xc2x0 C., a changing amount in a downward direction (in a arrow b direction) was approximately 0.4 mm at the center portion in the longitudinal direction of the developing blade 102.
When temperature is lowered, on the other hand, the deforming direction becomes in an upward direction in FIG. 15 (in an arrow c direction) which is an opposite direction when the temperature becomes higher, and therefore, a pressingly contacting force of the developing blade 102 becomes increased at the center portion in the longitudinal direction. Due to this, the thickness of the toner coat and the sliding-rubbing charging amount on the developing roller 101 become increased, and then an image density at the center portion in the longitudinal direction becomes higher, which might cause image unevenness.
Also, when the temperature inside the image forming apparatus rises, the cleaning frame 107 and the cleaning blade 106 shown in FIG. 16 becomes elongated in the right and left directions in FIG. 15 (in an arrow a direction) according to respective coefficients of thermal expansion, in the same way as that of the aforementioned developing container 104 and the developing blade 102 shown in FIG. 15.
At this time, as for the cleaning frame 107 made of resin and a sheet metal portion 106b, made of metal, of the cleaning blade 106, the cleaning frame 107 made of resin has a larger coefficient of liner thermal expansion and a larger elongation than those of the sheet metal portion 106b, thereby deforming the sheet metal portion in a downward direction in FIG. 15 (in an arrow b direction) based on the screws 103 as base points provided in the two spots, and therefore, the flexure angle xcex82 at a center portion in a longitudinal direction of the cleaning blade 106 shown in FIG. 16 becomes smaller, with the result that a pressingly contacting force of the cleaning blade 106 with respect to the photosensitive drum 105 becomes decreased at the center portion in the longitudinal direction and the intrusion amount Q with respect to the photosensitive drum 105 also becomes decreased, thus to cause problems such as a cleaning insufficiency or the like.
When temperature is lowered, on the other hand, the deforming direction becomes in an upward direction in FIG. 15 (in an arrow c direction) which is an opposite direction when the temperature becomes higher, and therefore, a pressingly contacting force of the cleaning blade 106 becomes increased at the center portion in the longitudinal direction, and the intrusion amount Q with respect to the photosensitive drum 105 becomes in excess. Thus, when an inappropriate portion of the elastic portion 106a of the cleaning blade 106, instead of the tip of the elastic portion 106a which is originally designed to be contacted with a surface of the photosensitive drum 105, is contacted with the surface of the photosensitive drum 105, cleaning insufficiency occurs; for example, residual developing agent, which is supposed to be scraped off, on the surface of the photosensitive drum 105 goes by to remain thereon. In addition, the photosensitive drum has been rubbed for a long time, which then causes problems such as a shorter lifetime of the photosensitive drum 105.
An object of the present invention is to provide a developing apparatus which absorbs a difference between elongation and contraction of a regulating member and elongation and contraction of a main body of the developing apparatus.
An another object of the present invention is to provide a cleaning apparatus which absorbs a difference between elongation and contraction of a cleaning member and elongation and contraction of a main body of the cleaning apparatus.
A still another object of the present invention is to provide a developing apparatus in which a positional relation between the regulating member and a developing agent carrier is not changed, irrespective of temperature changes.
A still another object of the present invention is to provide a developing apparatus in which a positional relation between the cleaning member and a body subjected to a cleaning process is not changed, irrespective of temperature changes.
Still further object and characteristics will be clear by reading the detail description of the invention described below with reference to accompanying drawings.